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Message-ID: <20231220224504.646757-24-david@redhat.com>
Date: Wed, 20 Dec 2023 23:44:47 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
David Hildenbrand <david@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Hugh Dickins <hughd@...gle.com>,
Ryan Roberts <ryan.roberts@....com>,
Yin Fengwei <fengwei.yin@...el.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Muchun Song <muchun.song@...ux.dev>,
Peter Xu <peterx@...hat.com>
Subject: [PATCH v2 23/40] mm/rmap: introduce folio_remove_rmap_[pte|ptes|pmd]()
Let's mimic what we did with folio_add_file_rmap_*() and
folio_add_anon_rmap_*() so we can similarly replace page_remove_rmap()
next.
Make the compiler always special-case on the granularity by using
__always_inline.
We're adding folio_remove_rmap_ptes() handling right away, as we want to
use that soon for batching rmap operations when unmapping PTE-mapped
large folios.
Signed-off-by: David Hildenbrand <david@...hat.com>
---
include/linux/rmap.h | 6 ++++
mm/rmap.c | 82 +++++++++++++++++++++++++++++++++++---------
2 files changed, 72 insertions(+), 16 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index bf6cb79aa7a0a..57e045093f047 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -243,6 +243,12 @@ void folio_add_file_rmap_pmd(struct folio *, struct page *,
struct vm_area_struct *);
void page_remove_rmap(struct page *, struct vm_area_struct *,
bool compound);
+void folio_remove_rmap_ptes(struct folio *, struct page *, int nr_pages,
+ struct vm_area_struct *);
+#define folio_remove_rmap_pte(folio, page, vma) \
+ folio_remove_rmap_ptes(folio, page, 1, vma)
+void folio_remove_rmap_pmd(struct folio *, struct page *,
+ struct vm_area_struct *);
void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *,
unsigned long address, rmap_t flags);
diff --git a/mm/rmap.c b/mm/rmap.c
index 2b386b9f6791c..1273180753953 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1510,25 +1510,37 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
bool compound)
{
struct folio *folio = page_folio(page);
+
+ if (likely(!compound))
+ folio_remove_rmap_pte(folio, page, vma);
+ else
+ folio_remove_rmap_pmd(folio, page, vma);
+}
+
+static __always_inline void __folio_remove_rmap(struct folio *folio,
+ struct page *page, int nr_pages, struct vm_area_struct *vma,
+ enum rmap_level level)
+{
atomic_t *mapped = &folio->_nr_pages_mapped;
- int nr = 0, nr_pmdmapped = 0;
- bool last;
+ int last, nr = 0, nr_pmdmapped = 0;
enum node_stat_item idx;
- VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
- VM_BUG_ON_PAGE(compound && !PageHead(page), page);
-
- /* Is page being unmapped by PTE? Is this its last map to be removed? */
- if (likely(!compound)) {
- last = atomic_add_negative(-1, &page->_mapcount);
- nr = last;
- if (last && folio_test_large(folio)) {
- nr = atomic_dec_return_relaxed(mapped);
- nr = (nr < COMPOUND_MAPPED);
- }
- } else if (folio_test_pmd_mappable(folio)) {
- /* That test is redundant: it's for safety or to optimize out */
+ __folio_rmap_sanity_checks(folio, page, nr_pages, level);
+
+ switch (level) {
+ case RMAP_LEVEL_PTE:
+ do {
+ last = atomic_add_negative(-1, &page->_mapcount);
+ if (last && folio_test_large(folio)) {
+ last = atomic_dec_return_relaxed(mapped);
+ last = (last < COMPOUND_MAPPED);
+ }
+ if (last)
+ nr++;
+ } while (page++, --nr_pages > 0);
+ break;
+ case RMAP_LEVEL_PMD:
last = atomic_add_negative(-1, &folio->_entire_mapcount);
if (last) {
nr = atomic_sub_return_relaxed(COMPOUND_MAPPED, mapped);
@@ -1543,6 +1555,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
nr = 0;
}
}
+ break;
}
if (nr_pmdmapped) {
@@ -1564,7 +1577,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
* is still mapped.
*/
if (folio_test_large(folio) && folio_test_anon(folio))
- if (!compound || nr < nr_pmdmapped)
+ if (level == RMAP_LEVEL_PTE || nr < nr_pmdmapped)
deferred_split_folio(folio);
}
@@ -1579,6 +1592,43 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
munlock_vma_folio(folio, vma);
}
+/**
+ * folio_remove_rmap_ptes - remove PTE mappings from a page range of a folio
+ * @folio: The folio to remove the mappings from
+ * @page: The first page to remove
+ * @nr_pages: The number of pages that will be removed from the mapping
+ * @vma: The vm area from which the mappings are removed
+ *
+ * The page range of the folio is defined by [page, page + nr_pages)
+ *
+ * The caller needs to hold the page table lock.
+ */
+void folio_remove_rmap_ptes(struct folio *folio, struct page *page,
+ int nr_pages, struct vm_area_struct *vma)
+{
+ __folio_remove_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
+}
+
+/**
+ * folio_remove_rmap_pmd - remove a PMD mapping from a page range of a folio
+ * @folio: The folio to remove the mapping from
+ * @page: The first page to remove
+ * @vma: The vm area from which the mapping is removed
+ *
+ * The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
+ *
+ * The caller needs to hold the page table lock.
+ */
+void folio_remove_rmap_pmd(struct folio *folio, struct page *page,
+ struct vm_area_struct *vma)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ __folio_remove_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);
+#else
+ WARN_ON_ONCE(true);
+#endif
+}
+
/*
* @arg: enum ttu_flags will be passed to this argument
*/
--
2.43.0
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